Question

Android Studio (Java)

I'm trying to create a simple calculator. I want to put out a message if they try to divide by 0.

I have this so far. What code should I put?

divide.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        if (number1.getText().length() != 0 && number2.getText().length() != 0) {
            double n1= Double.parseDouble(number1.getText().toString());
            double n2= Double.parseDouble(number2.getText().toString());

            double res= n1 / n2;

            result.setText(String.valueOf(res));
        } else {
            Toast.makeText(view.getContext(), "Please enter the numbers properly", Toast.LENGTH_SHORT).show();
        }
    }

});

Answer 1

Thanks for the question! Before doing the division n1 by n2, we need to ensure n2 is not equal to zero. 

We need to provide a checking just before we do that division, below is the updated code as how you need to do the checking. Please update the error message accordingly.

=============================================================================================


divide.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View view) {
         if (number1.getText().length() != 0 && number2.getText().length() != 0) {
             double n1= Double.parseDouble(number1.getText().toString());
             double n2= Double.parseDouble(number2.getText().toString());

             
             // validate the denominator n2 is not zero before doing the division
             if(n2!=0){
                 double res= n1 / n2;
                 result.setText(String.valueOf(res));
             } else {
                 Toast.makeText(view.getContext(), "ERROR. INVALID OPERATION. DIVISION BY /0", Toast.LENGTH_SHORT).show();
             }
         } else {
             Toast.makeText(view.getContext(), "Please enter the numbers properly", Toast.LENGTH_SHORT).show();
         }
     }

 });